The present invention relates to an improved method for coating carbon on the surface of a metal substrate or a metallized substrate. Furthermore, it concerns with parts of electron tube having black carbon coating on their surface and a method for production thereof. Thus, obtained carbon coated part of electron tube such as anodes, grids or shadow masks cause little generation of gases, are excellent in heat radiation efficiency, have extremely small secondary electron emission ratio and do not lose strong adhesiveness even at a high temperature of about 1,000.degree. C.
As the method for coating a metal surface with carbon, there has been known such method as applying a suspension of carbon using water glass as a binder by brushing or spraying. However, according to this method using water glass as a binder, the adhesiveness between the metal surface and carbon depends greatly upon the characteristic of the water glass. For example, when concentration of said water glass is high, said adhesiveness is great, but since the surface of carbon particles is protected by the water glass, the surface of the carbon layer cannot sufficiently exhibit the effect which it originally possesses. On the other hand, when concentration of said water glass is low, the adhesiveness between the metal surface and the carbon layer is small and the carbon layer is apt to separate from the metal surface.